CVE-2026-32836 in dr_libs
Summary
by MITRE • 03/17/2026
dr_libs dr_flac.h version 0.13.3 and earlier contain an uncontrolled memory allocation vulnerability in drflac__read_and_decode_metadata() that allows attackers to trigger excessive memory allocation by supplying crafted PICTURE metadata blocks. Attackers can exploit attacker-controlled mimeLength and descriptionLength fields to cause denial of service through memory exhaustion when processing FLAC streams with metadata callbacks.
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Analysis
by VulDB Data Team • 03/21/2026
The vulnerability identified as CVE-2026-32836 resides within the dr_libs library, specifically in the dr_flac.h component version 0.13.3 and earlier. This issue manifests as an uncontrolled memory allocation flaw that directly impacts the drflac__read_and_decode_metadata() function. The vulnerability is particularly concerning because it allows attackers to manipulate memory consumption patterns through carefully crafted PICTURE metadata blocks within FLAC audio files. The flaw operates by leveraging attacker-controlled fields within the metadata structure, specifically the mimeLength and descriptionLength parameters, which are processed without adequate validation or bounds checking. This vulnerability falls under CWE-770, which categorizes improper restriction of operations within a memory buffer, and represents a classic example of a resource exhaustion attack vector. The impact is particularly severe in environments where applications process untrusted FLAC streams, as the vulnerability can be exploited to consume excessive system memory resources.
The technical execution of this vulnerability involves the manipulation of FLAC metadata structures during the decoding process. When the drflac__read_and_decode_metadata() function processes PICTURE metadata blocks, it reads the mimeLength and descriptionLength fields directly from the input stream without implementing proper size validation. Attackers can craft malicious metadata blocks where these fields contain extremely large values, causing the library to allocate memory proportional to these attacker-controlled sizes. The memory allocation occurs during the metadata processing phase, which typically happens before the actual audio data is decoded, making this a particularly effective denial of service vector. The flaw demonstrates poor input validation practices and lacks proper bounds checking mechanisms that would normally prevent such unbounded memory allocation patterns. This vulnerability is consistent with ATT&CK technique T1499.004, which describes network denial of service attacks through resource exhaustion.
The operational impact of CVE-2026-32836 extends beyond simple denial of service conditions, as it can severely compromise system stability and availability. Applications that utilize the affected dr_libs library for FLAC stream processing become vulnerable to memory exhaustion attacks, potentially causing system crashes, application hangs, or complete system instability. The vulnerability is particularly dangerous in server environments where multiple concurrent connections are processed, as a single malicious stream can trigger cascading failures. When exploited, this vulnerability can lead to significant service disruption, especially in applications that do not implement proper memory allocation limits or timeout mechanisms. The memory consumption pattern is exponential in nature, as the library allocates memory based on the attacker-controlled field values, making it difficult to predict or prevent the exact impact of a successful exploitation. Systems that process large volumes of audio streams, such as media servers, streaming platforms, or content processing applications, face the highest risk of being affected by this vulnerability.
Mitigation strategies for CVE-2026-32836 primarily focus on immediate remediation through library updates and implementation of defensive programming practices. The most effective immediate solution is to upgrade to a patched version of dr_libs that addresses the uncontrolled memory allocation issue in dr_flac.h. Organizations should also implement input validation measures at the application level, including setting maximum limits for metadata field sizes and implementing proper timeout mechanisms during stream processing. The vulnerability can be mitigated through code-level defenses such as implementing bounds checking for mimeLength and descriptionLength fields, establishing memory allocation limits, and employing proper error handling for malformed metadata structures. Additionally, deploying intrusion detection systems that monitor for unusual memory allocation patterns can help detect exploitation attempts. Organizations should also consider implementing sandboxing or containerization techniques for applications processing untrusted audio streams, as this provides an additional layer of protection against resource exhaustion attacks. The remediation process should include comprehensive testing to ensure that the patched library functions correctly while maintaining the intended functionality of the audio processing pipeline.